The overall objective of the proposed research as new implantable radiotelemetry systems enabled by novel integrated sensors and circuits and inspired by the unique needs of biomedical research using chronic animal models of human physiology, pathology and pharmacology. Principal specific aims for the next year are: (1) Development of a new ultrasonic flow transducer cuff for use on small vessels such as coronary arteries. 2) Development of an infrared remote command transmitter link to control actuation of implantable telemetry units. 3) Repackaging of external electronics in a modern standardized "Eurocard" format to improve reliability, serviceability and flexibility in configuring new systems. 4) Initial in-vivo testing of integrated pH sensors using on-chip complimentary metal-oxide-semiconductor signal processing circuits and inclusion of membrane encapsulation to achieve selectivity among several ionic species. 5) Completion of design and demonstration of third generation on-chip circuitry for a miniature capacitive pressure sensor; continued development of laser welded packages; and initiation of in-vivo testing; design of an asynchronous digital multiplexer chip for use with multiple (pressure) sensors. 6) First in-vivo testing of an implantable photospectrometric blood oximeter system. 7) Fabrication of a prototype implantable ultrasonic dimension sensor using a wide dynamic range logarithmic amplifier in the ultrasonic receiver. 8) Fabrication of a new flexible telemetry transmitter integrated circuit to achieve increased range for pulsed Doppler ultrasonic flowmeter implants. 9) Initial in-vivo testing of a prototype 8-channel neurophysiological telemetry system. 10) Design of a multichannel pulsed Doppler ultrasonic flowmeter. Presently available systems as well as those cited in the previous paragraph will be applied in continued collaborative studies of hepatic hemodynamics in dogs, fetal and neonatal physiology in monkeys, cardiovascular pharmacology and electrophysiology in dogs, neurogenic hypertension in primates, narcolepsy in dogs, hydronephrosis in pigs, spinal orthopedics in sheep, thermoregulatory mechanisms in rabbits, and cellular mechanisms of cardiac hypertrophy in rats.